Becoveby of by-products of sugab extraction



Sept. 6, 1932.4 E. A. vAzQul-:z v

RECOVERY oF isi-PRODUCTS oF SUGAR ExTRAcTI'oN IFired oct. s1.. 1930 Www. Y@ Y@ Panarea sept. yc, 1932 UNITED sTArEs-PATENT OFFICE l RUcENIo -ANTONIO VAZQUEZ, or HABANA, CURA, AssIGNoR To vAzcANR PRocEss,

ING., A coRroRA'rIoN or :DELAWARE I RRcovRRY or RirlrRonUcfrsor SUGAR R'xirRAcrIoN l Application led October 3l, 1980. Serial No. 492,547.

Thisinvention relates'to a process for the' treatmentv of sugar cane and of the components derived therefrom, by which there 1s produced vsugar and ber pulp as the mam 5 products, and volatile organic compounds as by-products. v

It is customary in the process of isolatlng the sugar contained in sugar cane to'pass the cane through a series of heavy crushing mills or rolls, either as received at the mill or previously cut or shredded. The juice or. sugar bearing liquids are extracted or' expressed from the plant tissues by meansl of heavy pressure exerted by the crushing rolls. These rolls are of cast iron, weighing as hi h as fteen tons each, and the cane is passe successively through several sets of such rolls adjusted progressively closer together. Between the successive sets of rolls it is customary to add dilute juice from the'set of rolls` next in line (or water as maceration or imbibition water) for4 the purpose of obtaining a higher extraction of the available sucrose. From the last roll the woody refuse of the cane, called bagasse or megasse, is delivered containing ap roximately 50% moisture and in the state oismall ber aggregates. T'he bers are not individually se arate, but'are still bound to ther in bun les by the binding or cementitious materials in the'cane.

The customary method of disposal of thev bagasseor waste refuse is as fuel for a source of power for the sugar mills. In recent years, however, due to the diminishing supply of forest wood, other sources of supply vof ber pulp for paper making have been exploited, and bagasse has been the subject of a considerable amount of experimenting. `Bagasse has been used in the production of insulating xwallboard, but its physical state in such a wall-board is that' of dry grass or hay, rather than that'of paper pulp. l`However, the use of sugar cane as a raw material from which to manufacture mechanical paper pulp has recently been accomplished by a process set out in Letters Patent N o. 1,688,904, granted to me October 23rd, 1928.

'50 In this process the cane is separated, by

product, and also to obtain from the bagasse grinding or abrad'ing it, into individual bers l or agregates of relatively few bers, smaller than ave ever been produced by any prior methods of sugar recovery. The sugar 1s removed, or obtained, from this material by a method such as diffusion. The comminuted material is dispersed in a solvent bath, in which it is agitated-until the solvent is thoroughly worked into the bers. The solvent is then separated from the comminuted cane and the latter redispersed` in a second bath. In this bath the material is again agitated in the same manner as in the first, after which, it is again separated. 'i These stapsl'of dispersing, agitating and separating' re repeated as 65.' often as is necessary to complete the separation of sugar from the cane.

Water is used as the solvent only in the last dispersing treatment. Prior to the last treatv ment the solvent is the dilute sugar solution 7 from a subsequent dispersin stage. In other Words, the solvent is circu ted countercurrent'to vthe cane, freshwater being added to the nal bath, and the solution-from eachbath becomes-the solvent liquid for another u bath until it is removed from the rstl bath as concentrated sugar solution and delivered to the sugar boiling house.

The pulp resulting from the application of the process of my Patent No. 1,688,904'is much ner and much more uniform than ordinaiybagasse, but can be used equally as well as ordinary ba' asse for the production of ber pulp` according to my present invention. Y

M present invention is a process whereby the agasse, from which the sugar has been removed, is so treated as to obtain therefrom bers whose chemical composition and physical state differ from the original ber in such a way that the ber is suitable for use in the manufacture of wall-board, corrugated board, wrappin paper, newsprint paper, higher gradeso paper or any otherpaper other products of commercial value which are contained therein or chemically formed there-from. This process is applicable both to the usual sugar mill process whereby the cane is shredded or torn and the juice then ma new process is so carried out that the bagasse taken from a sugar mill during the active period is stored in treating tanks where it undergoes one of ythe steps necessary in its treatment while the sugar mill is finishing its period of active operation. This step consists of the treatment of the bagasse by storing it in large vats 0r tanks and completely covering it with a dilute lime solution. The solution is allowed to remain in contact withl the bagasse for a period of time sufficient for it to react with the bindingor cementitious materials which hold the fibers together in fiber bundles, and to dissolve or extract these materials from the bagasse. This is usually accomplished in a period of from three to four months or even less, depending upon the concentration of the lime solution and local conditions.

the fiber,

In the ordinary processes for the production of fiber pulp from bagasse or other woody material, the material is submitted to' a digestion usually under heat and pressure with certain alkalies. In order to remove completely the incrusting matter, the time of cooking, the presssure and strength of alkali have to be adjusted for digesting or cooking vvthe hardest parts of the fiber. This treatment is too drastic for the finer or weaker parts of and consequently the yields are low.

In the process of the present invention the action is veryv mild, the time for `reaction is considerable and the yield is ltherefore substantially great as compared with the cooking process. B the time the incrusting mate-l rials have een removed from the bagasse,

. the sugar inill has finished its normal operation andhas become inactive. Its equipment therefore becomes availablefor the further stepsof my process. The bagasse pulp which has been in storage may be freed from the lime solution by passing it through the' cane mills using imbibition water for washing` theV same as the cane `was originally treated lfor the removal of sugar, or the bagasse pulp may be passed through a dispersing,l agitat.

ing and screening system with a counter-y ilow system suchV as disclosed ,in myy priorpatent n nentionedV above. By this treatment the pulp and liquid are mechanically ex pressed or agitated, so as to Jfree completely the fibres of the pulp and to leave in the lime solution the cementitious or binding materials which have been rendered soluble. The fibrous pulp may be dried after the re.-

-moval of the lime solution, orl may be 'Gli bleached or subjected to a beating and refinterasse ing operation and lapped, or may be used i directly in the manufacture of paper.

l have obtained yields of of unbleached pulp on the basis of dry Cuban bagasse employed, and vof 44.7% of bleached pulp on the basis of dry Cuban bagasse employed. The lime solution remaimng after the removal of the pulp is passed on through the Settling tanks or filters of the sugar mill, where the sludge which has formed therein is removed. rThis sludge contains a large part of the lime which is used in the treatment of the bagasse in the form of phosphoric or organic acid salts, together with a certain amount of humus-like material.

This sludge may be treated by burning to rel cover the lime, or may tilizer. Another possible use for this sludge. lies yin the recovery of the-oragnic salts of calcium as such. It is obvious that still other treatments may be used to recover the valuable components in still different combinations.

The liquid from the filters is passed on into the evaporators of the sugar mill. slight changes in these evaporators they lmay be converted to function as fractionating stills and the lime solution may be fractionated so as to recover the volatile compounds formed from the bagasse. Such volatile com ounds vary in kind and quantity, depen ing upon t tion used and the time of treatment. After the volatile organic constituents of this lime solution have been recovered, the liquor may be further treated to obtain all or a part of the soluble solids it contains.

A flow sheet which forms a part of this description shows in diagrammatic form the steps of this process and may be referred to in connection with' the following detail description of the operation of this process.

. As shown at the left of the iiow sheet the untreated cane is rst subjected to a shredding or tearing treatment in what is ordinara crusher or hammer mill. After this treatment the cane is subjected to the crushing action of the sugar mill proper, wherein the heavy crushing rolls express the saccha rine juices from the cane. During this treatment water is usually added to complete the removal of the sugar. The course of the cane in receiving this treatment is shownby the fullline startin with the untreated cane and passing throug the steps of shredding or Vtearing' and of crushing. i Tt will be noted that water is indicated as being added at thecr'ushing step. This is customary although not absolutely essential.

With

be used directly as fere strength of the lime soluroe An alternate method of treatin the cane ing it in water. rlhis dissolves the sugar juices which are then removed by straimng or screening. y

the crushing and screening and the dispersing and agitating and screening or straining are shown, but once on the flow she'et, it is obvious that these steps andthe other steps ofthe process as well may be repeated' several times in order to make the treatment of the cane complete.

The two alternate processes shown differ only up to the point where the fibers are screened or strained from the aqueous suspension, and the flow sheet shows only one process from this point on.

The fibrous material from the last roll ofy the crushing mill is commonly known as bagasses. The bagasse is generally considered vas practically free' from sugar but usually -50% moisture.

contains a small quantity, and contains about The individual fibers of bagasses are bound together by the cementi-v tious material therein. This material contains 'the lignin and the pentosan constituents of the cane.

Thejuice expressed by the mills or removed from the dispersing tanks passes into settling tanks where it is treated with lime and the foreign matter therein allowed to settle out.` It usually then asses through tlters where the last partie es of foreign matter, bers', sludge, etc. are rremovedn From the lters the sugar solution passes into the usual evaporators where it is evaporated and the sugar crystallized.

The parts of the process set out above is.

that lof the usual sugar extraction rocess and is intended to be described mere y as a' basis upon which to build the following process'which is my invention. The process referred to above being theusual sugar process, it is obvious that changes known in the art and modifications of this process may be made without departing from the spirit of i my invention.

y invention comprises the superimposing of the following-process on to the usual sugar making process, and this added process is shown by the double lines which start with the bagasse taken from the'expressing mills in the usual sugar process.

' The bagasse from the usual' sugar process is placed, according to my process, in large vats or tanks where it is covered with a solution of lime and allowed to remain for a suiiicient time for the lime'to react with the constituents ofthe bagasse, which bind the individual yfibers together, sufficiently to loosen these fibers. TheI particular solution which I have found preferable is a solution containing approximately '5% lto 10% ofi.

lime based on the -dry weight of the fiber.

` The bagasse is preferably allowed to remain completely covered with lime solution for. a

prolonged period, usually about three or ,four

vent evaporation. The lon months. The tanksmay be covered to preperiod of storage not only allows the ime to react properly with the bagasse, vbut also provides time in which the sugar mill may finish its seasons workvof isolatin sugar and thus have its equipment availa le for use in the e treatment of the bagasse. The bagasse and lime solution are fed either to the crushing or dispersing and agitating equipment, depending upon which the two processes is in use in the sugar mill. After whichever of these two treatments isused the, bagasse andlime solution is screened or'strained. Y The-agita# l tion received either in the crushing or in the dispersing and agitating treatment com' is then filtered if required. The sludge which settles from the liquid at this time contains a large part 'ofA the lime used inthe treatment of the bagasse. This material is usually inthe form of salts of phosphoric and organic acids.l Various methods may be used for the recovery of the valuble constituents of this sludge. The sludge may be burned whereby the lime is recovered, or it may beused directly as fertilizer where it has particular value because of its nitrogen and phosphorous content. The nitrogen is acquired from the bagasse during the treatment thereof. AThe organic salts may also be recovered as such.

The resulting clear liquid is conducted as shown by the double lines) to the evaporating or fractionating apparatus.-` In using this process the evaporators used in thev normal sugar process are converted' by making some minor changes sothat they will function to fractionate this liquid. l FromV this fractionation various volatile organic compounds are obtained.. The liquor may be further treated for the recoveryof the solublesolids it c011- i tains.

. On the ow sheetthe usual. steps in the process of extracting and isolating sugar are shown as rectangular blocks and the usual course of materials passingthrough such a process is shown by a-single line. An alternate process such as described in my prior A Patent No. 1,688,904, granted to me. October 23rd, 1928, is shown in dotted lines. The

materials fed into the processand taken from the process at various stages are shown in the sugar mill is completed vbagasse and treating liquor to the sugar mill n mersing the bagassein lime at Ynormal temperature for a sufficient l subjecting the solution and fibers to light me-j the recovery of circles. Thus, in the usual sugar processuntreated cane passes through the shredding or tearing step through the crushing step 1n Which the Water is added; the juice flows t9 the screening or 'straining step While the bagasse is taken to be used as fuel under the boilers, and the juice' continues to the settling and filtering step from Which foreign material is discarded and through the evaporating step from which sugar is taken.

rlhe steps added by my improved. process are shown on the fioW sheet enclosed in octagon shaped boxes, and the flow of material through these steps and their return through certain steps in the usual sugar process are shown by double lines which start from the bagasse and run through the crushing or through the dispersing'and agitating step to the screening or straining step and on. The products produced by this process are shown below the steps of the process, fibrous pulp, sludge, volatile organic compounds and the soluble solids of the mother etc., and the products which may be produced from these materials.

1. The process of extracting sugar from sugar cane and recovering byproducts therefrom Which consists in extracting sugar from cane in the usual manner, storing the bagas'se derived from this extraction in a solution of lime until the normal period of operation o and returning the and subjecting it to treatment therein analogous to that of the sugar extraction process g to obtain fiber, pulp and other byproducts therefrom. j e

Q. The process of preparing bagasse for comprises immersing the bagasse in a dilute solution of lime at normal temperature for a sufficient length of time to loosen the fibers therein.

3. The process of preparing bagasse for the recovery of by-products and fibers which comprises treating the bagasse at normal temperature with a solution containing a Weight of lime equal to approximately 5% to 10% of the weight of the air-dry fibers to liberate the fibers therein.

4f. rlvhe process of preparing bagasse for the recovery of ley-products and fibers which comprises immersing the bagasse in a dilute solution of lime at normal temperature for a sufficient length'of time to loosen the fibers therein and subjecting the solution and fibers to light mechanical agitation to complete the .freeing of the fibers.

5. The process of recovering by-products and fibers from' bagasse which comprises ima dilute solution of length of time to loosen the, fibers therein,i

and are the `P f from bagasse which by-products and fibers which` maratea.

chanical agitation to completel the freeing of the fibers and separating theI solution from the fibers.

6. rlhe process of recovering by-products and fibers from bagasse which comprises immersing the` bagasse in a lime at normal temperature for a sucient length of time to loosen the fibers therein, and. se arating the solution from the bers.

The process of recovering by-products and fibers from bagasse which comprises immersing the bagass'e in a dilute solution of lime at normal temperature for a sucient length of time to loosen the fibers therein and separating the solution from the fibers by counter-current washing.

8. The processlof recovering by-products from bagasse which comprises treating the bagasse with adilute solution of limeat normal temperature and over a considerable eriod of time, separating the solution from dilute solution of y the fibers and distilling from the solution the products extracted from the bagasse.

9. The process of recovering Jbj1-products from bagasse which comprises treating the bagasse With a solution of lime a normal temperature for a sufficient lengt of time to loosen the fibers therein and recovering from the alkaline solution productsextracted from vthe bagasse. l

10. The process of recovering by-products comprises immersing the bagasse in a dilute solution of lime at normal temperature for a sufciemt length of time to loosen the fibers therein, subjecting the baasse to light mechanical agitation to com-y pletely free the fibers, separating the solution from the fibers and separating the sludge from the solution.' Y y Y 11. The process of recovering byfproducts from bagasse which comprises immersing the bagasse in a dilute solution of lime at normal temperature a sufficient length of time to loosen the fibers therein, separating the solun tion from` the fibers and separating the sludge from the solution.

12. The process as which the sludge is separated from the solution by settling and filtering.

13. rllhe process of recovering icy-products i from ba asse which comprises immersing the bagasse in a dilute solution of lime at normal temperature for a sucient length of time to loosen thel fibers therein, subjecting the bagasse to light mechanical agitation to completely free the fibers, separating the solution from thefibers, separating` the sludge from the solution, and recovering the products extracted by the solution.

14. The process of recovering by-products from bagasse which comprises immersing the bagasse in a dilute solution of lime at normal temperature for a suicient length of time to liberate the fibers therein, separating the so lution and fibers and removing 'a portion of defined in claim 11 inthe materials extracted from the bagasse as solids and distilling the remainder.

15. The process of recovering by-products from bagasse which comprises immersing the bagasse in a dilute solution of lime at normal temperature for a 'suicient length of time to liberate the fibers therein, separating the so lution from the fibers7 distilling from the solution a portion of the products extracted :from the bagasse, and recovering other products extracted from the bagasse as alkaline' organic salts.

16. The process of recovering' by-products from bagasse which comprises covering the bagasse with a dilute solution of lime, allowing it to stand so covered for several months at normal temperatures, subjecting the solution and bers to light mechanical agitation, separating the solution from the fibers by counter-current Washing,I and straining, settling and ltering the solution, burning the foo' sludge thus obtained to recover the lime therein and fractionally distilling the filtered I., solution to obtain furfural and vanillin.

In testimony whereof I ax' my signature. EUGENIO ANTONIO VAZQUEZ.' 

